Question

lx-3l+5 = 2x-9

giải giúp mình nha

Answer 1

`|x-3|+5=2x-9`

`@TH1: x-3 >= 0<=>x >= 3 =>|x-3|=x-3`

  `=>x-3+5=2x-9`

`<=>x-2x=-9+3-5`

`<=>-x=-11`

`<=>x=11`  (t/m)

`@TH2: x-3 < 0<=>x < 3=>|x-3|=3-x`

    `=>3-x+5=2x-9`

`<=>-x-2x=-9-3-5`

`<=>-3x=-17`

`<=>x=17/3` (ko t/m)

Vậy `S={11}`

Answer 2

lx - 3l + 5 = 2x - 9

<=> |x - 3| = 2x - 14               (1)

TH1: x ≥ 3 => |x - 3| = x - 3

=> (1) <=> x - 3 = 2x - 14 <=> 11 = x (TM)

TH2: x < 3 => |x - 3| = -(x - 3) = 3 - x

=> (1) <=> 3 - x = 2x - 14 <=> -3x = -17 <=> x = 17/3 (KTM)

vậy x = 11